A conventional bit as shown in FIG. 1 includes a neck portion N recessed in a bit B and engaged by a locking ball L to be locked in an adapter H which is then clamped in a chuck C of a hand tool including an electric drill, a driver, an electrically charging tool, and a pneumatic tool.
However, the neck portion N as recessed in each bit, such as the numerals B, B1, B2, is not located at a constant position on the bit. Each bit should require a corresponding adapter or bit holder for well matching of the bit in the adapter, thereby requiring a plurality of adapters and increasing the installation cost.
Since the neck portion N is generally recessed in a deep portion within the adapter H, a large shank portion of the bit B will protrude outwardly beyond the adapter to cause unstable holding of the bit in the adapter. It also remains an aperture between the neck portion N and the locking ball L, thereby easily loosening the holding of the bit within the adapter.
The present inventor has found the drawbacks of the conventional bit adapter, and invented the present universal bid adapter.
The object of the present invention is to provide a universal bit adapter including: an adapting member clamped in a chuck or spindle of a tool having a shank hole longitudinally formed in the adapting member for inserting a tool bit into the shank hole; a sleeve coupled to a front portion of the adapting member for pivotally mounting a control member in a front portion of the sleeve; and a tension spring resiliently held in the sleeve for tensioning a back portion of the control member for normally biasing the control member to allow an axis of a central hole formed through the control member to be eccentrically inclinedly intersected with a longitudinal axis formed in the shank hole in the adapting member for firmly dogging any shank portion of the tool bit in the central hole in the control member regardless of the positioning of the neck portion as recessed in the shank portion of the tool bit.